1. Field of the Invention
The present invention relates to an apparatus for applying a primer on an outer surface of a work having rod shape.
2. Related Art Statement
Generally, in the case of manufacturing for example a polymer insulator, a primer (under-coating member such as adhesives) is applied on an outer surface of an FRP core having a rod shape as a work, and then a shed made of for example silicone rubber is molded thereon. In this method, an operation for applying the primer on the outer surface of the FRP core is performed such that, an operator moves gauze in which the primer is immersed on the outer surface of the FRP core in a longitudinal direction under a contact manner, while he rotates the FRP core every 120.degree.. Moreover, in this primer applying operation, if it is necessary to provide a portion, to which the primer is not applied, at both ends of the outer surface of the FRP core which are connected with a metal flange, a masking tape is adhered to the portion to which the primer is not applied, and then the primer applying operation is performed.
However, in the known primer applying method mentioned above, since the operator applies the primer manually, the primer applying operation takes a lot of time and also it is difficult to apply the primer uniformly on the outer surface of the work. Moreover, in the case of providing the portion to which no primer is applied, it also takes a lot of time since the masking tape adhering and removing operations are troublesome.
In order to solve these problems of the known primer applying method, the present application proposed an apparatus and method of applying a coating member in Japanese Patent Laid-Open Publication No. 9-24317 (JP-A-9-24317). FIG. 4 is a schematic view showing one embodiment of the apparatus mentioned above. In FIG. 4, an accommodating chamber 51 is provided on a supporting plate 53 through a receiving member 52, and is divided into a lower chamber 51a and an upper chamber 51b. The lower chamber 51a is fixed on the supporting plate 53 and the upper chamber 51b is provided detachably on the lower chamber 51a. A primer inlet 55 to which a primer supply pipe 54 is connected is provided on a top portion of the upper chamber 51b. An overflow hole 56 for overflowing the primer is provided at a side wall of the lower chamber 51a.
Moreover, an elastic member 57 made of sponge in which bubbles are communicated with each other is divided into a lower elastic member 57a and an upper elastic muter 57b along a partition line from a communication hole 58. The lower elastic member 57a is accommodated exchangeablly in the lower chamber 51a and the upper elastic member 57b is accommodated exchangeablly in the upper chamber 51b. Supporting members 59 are made of an elastic material such as rubber whose hardness is larger than that of the sponge mentioned above. The elastic member 57 is sandwiched by the supporting members 59 toward a moving direction of a work 60. Through holes 61 having a taper shape communicated with the communication hole 58 are formed respectively at centers of the supporting members 59. Each supporting member 59 is divided into a lower supporting member 59a and an upper supporting member 59b along a partition line from the through hole 61.
In the apparatus for applying a primer mentioned above, the primer is supplied continuously into the accommodating chamber 51 through the primer supply pipe 54 and the primer inlet 55, and is discharged from the overflow hole 56. Therefore, it is possible to maintain the elastic member 57 always at a moist state by the primer. If the work 60 is rotated and moved along a longitudinal direction under such a condition, it is possible to automatically apply the primer on a predetermined portion of the work 60.
However, in the apparatus for applying a primer shown in FIG. 4, the present applicant found that the following problems occur.
(1) Special shape is required for the elastic member (sponge) for applying the primer, and thus a forming operation of the elastic member requires a lot of working steps.
(2) Every time a diameter of the work is changed, it is necessary to prepare the elastic member corresponding to the diameter of the work.
(3) A specific primer such as silane used for an adhesion between the FRP core and silicone rubber in the polymer insulator is hardened if being brought into contact with a water component in the air but it is never softened again by a solvent. Since the elastic member, to which the primer is applied, is brought into contact with a water component in the air every time the work is changed, there is a limitation for a successive use and it is necessary to change the elastic member frequently.
(4) Since the primer discharged from the overflow hole is brought into contact with the air, the primer is not used again and must be scrapped.
(5) The primer is uniformly immersed into the lower elastic member, but is not uniformly immersed into the upper elastic member. This is because the primer is uniformly immersed into a portion of the upper elastic member just beneath the primer inlet but is not uniformly immersed into a portion of the upper elastic member remote from the portion just beneath the primer inlet. Therefore, the primer is wasted for a running operation from a start of the primer applying operation to a state in which the primer applying operation becomes stable, and also the primer applying operation takes a lot of time for the running operation.